Electrons emitted from field emission sources have been found useful in flat panel displays and vacuum microelectronics applications. Electron field emission is most easily obtained from sharply pointed needles, cones, or tips. U.S. Pat. No. 3,789,471 to Spindt, et al. and U.S. Pat. No. 5,141,460 to Jaskie, et al., which are hereby incorporated by reference herein, both disclose methods of making such micro-tips through lithography methods. However, such lithography methods require extensive fabrication facilities to finely tailor the emitter into a conical shape. Furthermore, with such fabrication methods, it is difficult to build a very dense field emitter, since the cone size is limited by the lithographic equipment. Furthermore. lithography is made even more difficult when the substrate area on which the microtips are to be constructed is of a large area, as is required by flat panel display type applications.
U.S. Pat. No. 5,199,918 to Kumar further discusses the disadvantages of the use of lithography for creating a field emitter device. U.S. Pat. No. 5,199,918 is hereby incorporated by reference herein. This patent teaches a method of fabricating a field emitter device by coating a substrate with a diamond film having negative electron affinity and a top surface with spikes and valleys, depositing a conductive metal on the diamond film, and etching the metal to expose portions of the spikes without exposing the valleys, thereby forming diamond emission tips which protrude above the conductive metal. One disadvantage of this method of fabricating field emitter tips is that the height and structure of the tips is limited by the crystalline structure of the diamond thin film deposited on the substrate.
Thus, what is needed in the art is a method of making a field emitter device that does not require the use of lithography and that is not limited to the crystalline structures provided by a diamond thin film.